US3604718A

US3604718A - Tong assembly for drill pipes

Info

Publication number: US3604718A
Application number: US831694A
Authority: US
Inventors: Floyd W Becker
Original assignee: Becker Drilling Alberta Ltd
Current assignee: Drill Systems International Ltd; Becker Drilling Alberta Ltd
Priority date: 1969-06-09
Filing date: 1969-06-09
Publication date: 1971-09-14
Anticipated expiration: 1988-09-14

Abstract

A tong apparatus for use with a rotary drill apparatus whereby threadedly engaged sections of drill pipe may be disconnected. The apparatus comprises: a mounting element for positioning around a section of drill pipe and spaced therefrom, a coaxial extension above said mounting element having means for connecting the apparatus to the power swivel of the rotary drill apparatus, at least one pivotal member on the mounting element rotatable about a pivot axis and having a pipe gripping portion for contacting the section of drill pipe when the pivot member rotates in one direction with respect to the mounting element and which moves away from the section of drill pipe when the pivotal member rotates in the other direction with respect to the mounting element. An inertial element is integral with the mounting element and is capable of movement with respect to the pivot axis and capable of urging the pivotal member to move tangentially about the pivot axis.

Description

United States Patent Primary Examiner-Andrew R. Juhasz Assistant Examiner-James F. Coan Attorney-William George Hopley ABSTRACT: A tong apparatus for use with a rotary drill apparatus whereby threadedly engaged sections of drill pipe may be disconnected. The apparatus comprises: a mounting element for positioning around a section of drill pipe and spaced therefrom, a coaxial extension above said mounting element having means for connecting the apparatus to the power swivel of the rotary' drill apparatus, at least one pivotal member on the mounting element rotatable about a pivot axis and having a pipe gripping portion for contacting the section of drill pipe when the pivot member rotates in one direction with respect to the mounting element and which moves away from the section of drill pipe when the pivotal member rotates in the other direction with respect to the mounting element. An inertial element is integral with the mounting element and is capable of movement with respect to the pivot axis and capable of urging the pivotal member to move tangentially about the pivot axis.

TONG ASSEMBLY FOR DRILL PIPES This invention relates generally to the rotary piercing of earth formations by means of a drill pipe, the upper end of which is rotated by a power swivel and the lower end of which carries a bit adapted to bite through the particular earth formation being pierced. More particularly, this invention relates to a tong apparatus for use as an accessory with rotary earthpiercing drills, and capable of gripping the drill pipe from the outside and rotating the same, even though the drill pipe itself be loosely threaded, or not threaded at all, into the power swivel.

In the rotary earth-piercing art, it is generally desirable to mechanize as much of the process as possible, in order to reduce the amount of manual labor required for a particular job, and thereby increase both the efficiency and speed of a particular operation.

The portion of a drilling operation to which this invention is particularly related is that which involves the disassembly of the segmented drill pipe after the drilling of a particular bore hole has been completed. Generally speaking, the sequence of events involved in disassembling a segmented drill pipe is obvious. The power swivel, which is usually hydraulically operated and is capable of vertical motion along an appropriate guideway, will have arrived, upon completion of the drilling, at a given point along its vertical path of movement. Assuming that this point is at or near the lower end of its path of movement, the drill pipe disassembly operation is carried out by raising the power swivel to a point at or near the top of its vertical movement path, carrying with it the entire length of drill pipe, whereupon the uppermost segment of drill pipe is unscrewed from both the power swivel and the segment next beneath the uppermost segment. Some sort of vise arrangement is required to grip the second segment in the line while the uppermost segment is being removed. Following this, the power swivel descends and engages the second segment (now the uppermost) and again lifts the entire length of the segmented drill pipe upwardly until it reaches the top of its travel. At this point, the third segment is gripped in the vise, and the second segment is unscrewed from the power swivel and from the third segment. This process is repeated until the entire length of the segmented drill pipe is disassembled.

The object of this invention is to provide an accessory for the power swivel mechanism which permits the tight threaded engagement of adjacent segments of drill pipe to be broken automatically, obviating the necessity of breaking the engagement manually.

Accordingly, this invention provides a tong assembly for selectively gripping and releasing a drill pipe, comprising: a mounting element for positioning adjacent a drill pipe without contacting the drill pipe, at least one pivotal member mounted on the mounting element to rotate about a pivot axis, the pivotal member having spaced from said pivot axis a pipegripping portion which moves toward and into contact with the drill pipe when the pivotal member rotates in one direction with respect to said mounting element and which moves away from the drill pipe when the pivotal member rotates in the other direction with respect to said mounting element, and an inertial element capable of movement with respect to said pivot axis and adapted, upon such movement, to urge a part of the pivotal member to move tangentially about said pivot axis.

One embodiment of this invention is shown in the accompanying drawings, in which like numerals denote like parts throughout the several views, and in which:

FIG. 1 is a schematic elevational view of nine sequential steps in the removal of a segment of drill pipe;

FIG. 2 is an elevational view of the tong assembly of this invention;

FIG. 3 is a view of the tong assembly of FIG. 2 looking from right to left at the end of the tong assembly;

FIG. 4 is a cross-sectional view of the tong assembly of FIG. 2 taken at the line 44 in FIG. 2; and

FIG. 5 is a partial sectional view similar to that of FIG. 4, showing one of the elements in FIG. 4 in a different position.

Turning first to FIG. 1, the general sequence of operations in the removal of one segment of a segmented drillpipe will be described. In FIG. 1, the sequential positions are denoted by the letters A-J, and take place in alphabetical order. In FIG. 1A the column 10 denotes the guideway or track along'which a power swivel 12 is vertically movable. The line 14 is a segmented drill pipe and the portion visible in FIG. 1A is the uppermost segment of the drill pipe. The uppermost segment of the drill pipe 14 extends downwardly into a drill hole 16 which is in the process of being drilled in FIG. 1A. The crossline 17 on the drill stem 14 denotes the point at which the drill stem 14 is threaded onto a rotary shaft 18 extending downwardly from the power swivel 12. A vise 20 is mounted on the column 10 and is represented by an anvil and a point, both schematically drawn. The tong assembly of this invention is shown at 22 and includes a vertical extension 23. The vertical extension 23 is securely threaded to an annular shaft 24 which extends downwardly from the power swivel 12 and is adapted to rotate with the shaft 18. The crossline at 25 denote the point at which the vertical extension 23 of the tong assembly 22 is threaded to the annular shaft 24.

The tong assembly 22 contains a pipe-gripping means which has been represented by two opposing arrows in FIG. 1. During the drilling operation shown in FIG. 1A, the arrows inside the tong assembly 22 are shown spaced away from the drill pipe 14, because the latter is entirely free of contact with the tong assembly 22 at this point. In FIG. 1A above the power swivel 12, the letter R is surrounded by a rotational arrow which indicates the direction of rotation of the tong assembly 22 as seen from above looking downwardly. Thus, in FIG. 1A, the drilling operation involves a continuous clockwise rotation of the shaft 18, the drill pipe 14 and, although of no importance at this point, the tong assembly 22.

It is now assumed that the drilling operation has been completed, and that the power swivel 12 has ceased to rotate the drill pipe 14. In FIG. 1B, rotation of the drill pipe 14 has stopped, and the vise 20 has been made to firmly grip the uppermost segment of the drill pipe 14. In FIG. 1C, the power swivel 12 is caused to rotate a fraction of a turn in the counterclockwise direction, and this breaks the tight threaded connection between the upper segment of the drill pipe 14 and the shaft 18 extending from the power swivel 12. The broken but still loosely engaged threaded connection between the upper segment of the drill pipe and the shaft 18 is represented in FIG. 1C by two horizontal crosslines linked together by brackets. This means that, although it is possible to rotate the shaft 18 with respect to the upper segment of the drill pipe 14, the threads of these two elements are still sufficiently engaged that the upper segment cannot be pulled vertically away from the shaft 18. Above the power swivel 12 in FIG. 1C, the rotational diagram denotes a fraction of one revolution beginning at the start S and being arrested at A.

In FIG. 1D, the power swivel 1215 not rotating, and the vise 20 has been withdrawn from engagement with the drill pipe 14. Throughout the remainder of FIG. 1 to be discussed, the numerals will be reduced to a minimum in order to avoid confusion.

In FIG. IE, the power swivel 12 has been raised to a point at or near the upper end of its travel, and has drawn with it the entire length of the drill pipe 14, including all of its segments, due to the fact that the threaded engagement between the upper segment of the drill pipe 14 and the shaft 18, although no longer a tight connection, is sufficient to bear the weight of the drill pipe 14. The power swivel 12 is thus raised to a position in which the threaded connection between the uppermost segment of drill pipe and the next lower segment is positioned above the vise 20.

As seen in FIG. IF, the vise 20 is next brought into engagement with the second segment, while the remainder of the ap paratus remains stationary.

In FIG. 1G a high-speed fractional rotation of the tong assembly 22 in the counterclockwise direction succeeds, by a mechanism later to be explained, in bringing the pipe-gripping elements within the tong assembly 22 into tight engagement with the uppermost segment of the drill pipe. In the rotational diagram above the power swivel 12 in FIG. 16, the fractional rotation begins at S and ends at A.

In FIG. 1H, now that the pipe-gripping means in the tong assembly is in engagement with the upper segment of the drill pipe, further counterclockwise rotation of the tong assembly 22 turns the upper segment of the drill stem, and causes the latter to be rotated with respect to the second segment. Because the vise 20 is restraining the second segment from rotation, the threaded connection between the two segments is broken. It is desirable at this stage to completely unscrew the upper segment from the segment beneath.

In FIG. 1.], another high-speed fractional rotation of the tong assembly 22, this time in the clockwise direction, succeeds in disengaging the pipe-gripping means within the tong assembly from the upper segment of the drill pipe 14. When the stage shown in FIG. H has been reached, the upper segment can be held manually while the power swivel I2 completely unscrews the shaft 18.

Turning now to FIG. 2, the tong assembly 22 is shown on its side: a lower cylindrical compartment 27 has a concentric cylindrical shaft 28 extending rightwardly (upwardly when in use) from the compartment 27. The shaft 28 is preferably of integral manufacture, and is seen to be provided with exterior threads 30 at its upper end, and a partly knurled expanded midportion 32. The cylindrical compartment 27 is defined generally between a first annular wall 34 which is fixed rigidly to the shaft 28, and a second annular wall 35 which is fixed rigidly to the first annular wall 34 by means of three internal pillars 38 which are shown in cross section in FIG. 4, and which extend perpendicularly between the two walls 34 and 35.

Attention is now directed to FIG. 4, which is a cross-sectional view showing the internal components of the compartment 27. Extending between the two walls 34 and 35 are three pivot pins 40, spaced at 120 intervals, and located approximately centrally between the outer periphery 41 and the inner periphery 42 of the annular walls 34 and 35. The inner periphery 42 of the walls 34 and 35 coincides with the inner circumference of the shaft 28 where it joins the annular wall 34.

Three pivotal members 44 are mounted to rotate about the pivot axes defined by the center lines of the pivot pins 40. The shape, size and operation of all three pivotal members are identical, and for this reason attention will be directed to the upper right-hand pivotal member 44 in FIG. 4 throughout the remainder of this description. The pivotal member 44 has been shown to be circular in cross section, and although it is convenient to provide the members 44 in the shape of discs, it will be appreciated that this shape is by no means essential to the invention. The pivotal member 44 supports a pipegripping jaw 46 at a location spaced from the pivot axis defined by the center line of the pivot pin 40. As can be seen in FIG. 4, the particular location of the jaw 46 with respect to the pivot pin 40 is such that the jaw 46 moves toward the drill pipe 14 when the pivotal member 44 rotates in the counterclockwise direction with respect to the annular wall 35, and moves away from the drill pipe 14 when the pivotal member 44 rotates in the clockwise direction with respect to the annular wall 35.

Mounted for loose and independent movement with respect to the two walls 34 and 35 is a cylindrical inertial element 48 the exterior surface of which is visible in FIG. 2, and a cross: sectional view of which is visible in FIG. 4. The inertial element 48 is provided with three tangentially elongated slots 50 at three locations spaced 120 from each other, and each pivotal member 44 has an outwardly extending pin 52 which passes through one of the slots 50 and has on its far end a head 53 the dimensions of which make it too large to pass through the slot 50. The mechanical interference between the head 53 and the slot is clearly seen in FIG. 2.

The element 48 is very heavy, and its inertia is utilized to move the pins 52 in one direction or another, thereby rotating the jaws 46 either into engagement or out of engagement with the drill pipe 14.

The operation of the tong assembly at the stage shown in FIG. 1G, wherein the jaws 46 are caused to swing inwardly and tightly grip the drill pipe 14, will now be described with particular reference to FIGS. 4 and 5. In FIG. 5, only one pivotal member of the tong assembly has been shown. FIG. 5 shows the position of the pivotal member 44 during all of the stages represented by FIGS. 1A through 1F. It is observed that the jaw 46 is withdrawn from engagement with the drill pipe 14. The high-speed fractional rotation of the power swivel 12 shown above FIG. 10 causes the wall 35 abruptly to move in the direction of the arrow T in FIG. 5. Naturally, the pivot pin 40 also undergoes this rapid movement. The drill pipe I4, however, which is at this point only loosely threaded to the shaft 18, does not rotate. Also, the element 48, because of its high inertia, does not rotate initially with the wall 35 unless it is already in the position shown in FIG. 5, wherein the upper left edge of the slot 50 is in contact with the pin 52, and the latter cannot move any further to the right (clockwise direction about the pivot pin 40) because the head 53 is binding against the longitudinal edges of the slot 50. If the element 48 is not in the FIG. 5 position, it remains stationary until the FIG. 5 configuration is reached, at which time a strong counterclockwise impetus is transmitted to the element 48, to start it rotating in the counterclockwise direction at the same speed as the wall 35. The tong assembly, and thus the wall 35, is then suddenly and abruptly stopped, which means that the pivot pin 40 is also abruptly stopped. The inertial element 48, however, continues to rotate in the counterclockwise direction, as shown by the arrows P in FIG. 4, and this continuing rotation brings the other edges of the slots 50 into smart contact with the pins 52, causing the pivotal members 44 to rotate in the counterclockwise direction at high speeds, driving the jaws 46 against the outer surface of the drill pipe 14. Once the jaws 46 have been thus locked against the surface of the drill pipe 14, the power swivel 12 can be further rotated in the counterclockwise direction, this time at slower speed, until the desired degree of unscrewing has been achieved (see FIG. 1H). As mentioned above, it is desirable to continue this slow-speed counterclockwise rotation until the threaded engagement between the uppermost pipe segment and the next lower pipe segment has been completely unscrewed. After the joint between the first and second pipe segments has been completely unscrewed, the jaws 46 can be disengaged from the outer surface of the drill pipe 14 by utilizing the inertia of the inertial element 48 in the same manner as before, but in the opposite direction. That is, the tong assembly is given a fraction of a turn in the clockwise direction at very high speed (carrying with it the upper segment of the drill pipe 14), and giving a clockwise impetus to the inertial element 48. When the clockwise rotation of the tong assembly is abruptly stopped, the inertial element 48 continues its clockwise rotation, coming into smart contact with the pins 52, and causing the pivotal members 44 to rotate in the clockwise direction and break the jaws 46 loose from the surface of the drill pipe 14. This latter sequence has not been illustrated in detail, as it will be obvious in view of the description of the engagement of the jaws 46 with the drill pipe 14, taking place in FIG. 1G.

It is desirable to provide an overtoggling biasing means which tends to maintain the heads 53 in either limit position, and such a means has been shown in FIGS. 2 and 3. Affixed to each head 53 is an extension which projects beyond the wall 34 and carries a pivoting member 56 to which one end of a helical compression spring 58 is attached. The other end of each compression spring 58 is attached to a projection 60 which is fixed to the wall 34. The attachment between the projection 60 and the spring 58 is such as to permit the compression spring 58 to swing through a limited are as the head 53 moves back and forth between its two limit positions shown in solid and dotted lines in H6. 3. Each projection 60 is situated generally between its respective head 53 and a point 62 which defines the axis about which rotates the pivot member 44 carrying that head 53. By locating the projection 60 approximately equidistant from the head 53 in its two limit positions, an overtoggling light-switch type of action is assured, in which the compression spring 58 is at its greatest length when the head 53 is in either limit position, and is at its minimum length when the head 53 is midway between its two limit positions.

It is pointed out that, although three pivotal members 44 have been provided in the embodiment illustrated in the drawings, the invention would be worked so long as there were at least one of such pivotal members provided with a jaw capable of engaging the surface of the drill pipe 14.

it will further be obvious that, although one particular form of the inertial element 48 has been shown, a number of other designs could be elaborated wherein a different construction, particularly for the inertial element 48, were employed. For

example a separate inertial element could be provided for each of the pivotal members 44. Again, the inertial element 48, instead of being mounted exteriorly of the pivotal members 44, could be mounted inside of the pivotal members 44. Such a design would likely mean that engagement of the jaws 46 with the drill pipe 14 would entail rapid fractional rotation of the tong assembly in the opposite direction from that shown and described above.

While one embodiment of this invention has been shown and described herein, those skilled in the art will appreciate that changes and modifications may be made therein without departing from the spirit and scope of this invention as defined in the appended claims.

1. A tong assembly for selectively gripping and releasing a drill pipe, comprising:

an annular mounting element for positioning adjacent a drill pipe and having a central aperture capable of receiving a drill pipe without contact, said element having a coaxial shaft extension at one end adapted to be threadedly secured to a power swivel of a drilling apparatus,

three pivotal members on the side of said annular mounting element remote from said coaxial shaft extension, said members spaced axially at approximately in the annular mounting element and each pivotal member adapted to rotate about a pivot axis in a plane normal to the axis of said drill pipe, each pivotal member having a pipe-gripping portion spaced from its pivot axis and moveable toward and in contact with said drill pipe when said pivot member rotates in one direction with respect to said annular mounting element and moves away from said drill pipe when the pivotal member rotates in the other direction with respect to said annular mounting element,

an annular inertial element loosely retained in said annular mounting element and capable of movement with respect to each of said pivotal members,

a part of each of said pivotal members projecting generally away from the pipe gripping portion through an opening in said inertial element whereby a sudden change in the rotational velocity of the annular mounting element results in a relative rotational movement between the annular mounting element and the inertial element thereby urging said part of each of said pivotal members to move tangentially about the pivot axis of the respective pivotal member.

2. A tong assembly as claimed in claim 1 which includes overtoggling bearing means adapted to urge said projecting part of at least one of said pivotal members in either one direction to maintain the pipe-gripping portion in pipegripping position or in the opposite direction to maintain the pipe-gripping portion away from pipe-gripping position.

3. A tong assembly as claimed in claim 2 wherein said annular mounting element has a first annular wall and a second annular wall rigidly secured to said first wall, said annular inertial element loosely retained between said first and said second wall.

Claims

1. A tong assembly for selectively gripping and releasing a drill pipe, comprising: an annular mounting element for positioning adjacent a drill pipe and having a central aperture capable of receiving a drill pipe without contact, said element having a coaxial shaft extension at one end adapted to be threadedly secured to a power swivel of a drilling apparatus, three pivotal members on the side of said annular mounting element remote from said coaxial shaft extension, said members spaced axially at approximately 120* in the annular mounting element and each pivotal member adapted to rotate about a pivot axis in a plane normal to the axis of said drill pipe, each pivotal member having a pipe-gripping portion spaced from its pivot axis and moveable toward and in contact with said drill pipe when said pivot member rotates in one direction with respect to said annular mounting element and moves away from said drill pipe when the pivotal member rotates in the other direction with respect to said annular mounting element, an annular inertial element loosely retained in said annular mounting element and capable of movement with respect to each of said pivotal members, a part of each of said pivotal members projecting generally away from the pipe gripping portion through an opening in said inertial element whereby a sudden change in the rotational velocity of the annular mounting element results in a relative rotational movement between the annular mounting element and the inertial element thereby urging said part of each of said pivotal members to move tangentially about the pivot axis of the respective pivotal member.

2. A tong assembly as claimed in claim 1 which includes overtoggling bearing means adapted to urge said projecting part of at least one of said pivotal members in either one direction to maintain the pipe-gripping portion in pipe-gripping position or in the opposite direction to maintain the pipe-gripping portion away from pipe-gripping position.